Refractometer



"March 2o, 194s.

A s. J. JACOBSOHN 'REFRAQTQMETE'R Filed sept. 144, 1942 2 sheets-sheet 1 WWWI j I Jzezfn. @Hadj/60550225 5MM@ @ma ym.

As. J. 'JAcosoHN March 20, 1945.

- l REFRACTOMETER `Filed Sfmt. 14, 1942 2 Sheets-Sheet 2 \u lllllllllllllllllllllllllllll I.

thddrlmlminwhich:

Patented Mar. 20, 1945 UNITED STATES `PATENT OFFICE mmcrommnn smud- J. Juanan. camara. m.. maar co The Gnertner Salentino Corporation, n corporation of Iliinois Application september 14.1942. sei-m m. 458.243

1 chum. (ci. ss-m A This'invention relates to u. retractometer. and

more 'particularly to a'n 'improved instrument oi Y Htmlisltopplan 'of the lixht whichis observed. the angle between andn'theietnctinindegotthe-primthis xglstloniszivenbythetormula.

thelizht ny striking this interface and. line Il perpendicular to the interface. When illumina.-

tion is from the side. as shown here.. and the angle ot incidence is large the reection from the interface is total, and the fleld viewed in the telescope is brightly illuminated: as the angie of incidence is reduced by movement of one oi the elements of the retractometer. however. a. point sion. When the lllht is transmitted through the interface. of oourse,t he held of view is dark. When illumination is throuzh a different lace, ot course, the light-dark relationship may be rewiui the :im n' or the .hilo n! iotaljretlection (that is, the mln1- theinterteomntherehnoveindexottheliquid,

added to a known weight ot water, the refractive index determined, and the moisture content of the com thus rapidly and quickly determined without the necessity of going through the longer median p oint'oi thetransition band.' In order to l effect this, Iidiv'idethe light the-front or. obiective oi my telescope into two halves. DASS* int onehalf of-thellght directly'through'the telescope to the eye-piece. I pass the otherhalf of the light', howeverr'throush a. reversingizarran'gef' ment .which 'reverses it symmetricailyabont-an 'axial piane-bmg thetelesoope: andthan I complte!! or Partially supernnvoe the two viewsthus provided. It the'movable element' of the reiractometer istoofatto one sideof correctsetf tink (the total reilectionside) 'there' is 'a bright band orfatxje'ak inthe oenter` of. theiieldywith 3v.. z darker portions on 'eachside:oi itfilithe 'settipzj is too f ar theother van there is aidarlrer-bandv "in the 'center,with`lihter portions-fo each sido 'of it; -but when the settinz is correet;.the shade. .otthe'neldis mitor'ni rchan'g'es of.,

' shade apparent. ev'ep to a relatively un skllledobse'r'ver'. when viewedinthis so l th'at accurate determinations can bemade-'and without any betweendiff` o reproduced xietentobservers.

tion metoforegben index of refraction-f'turbid liquids is not but itis believed that itrlhouldbeaooonsidered. and my relraletonietorA enables locmate: deter-` mination crit. '.'When}use.d; with a.4 homogeneous readigaasaoonventionalrelractometen-sridmy dev ioeoan kann into vthelield of' .1m me tion illustrated toletben and to be separated whendesired for prisml.: preferably un palanca faces Ila, IIb and' llc; while the face- Ila of the other prlnn is preferably ground. Other uf. in'y' invesherewith a'table il. Supports' a" viewedeletiient I l `.gimif methods of illumination may be used, but in the method here shown light enters through the face 12b. strikes the face lla which is in contact with the liquid there. ii conditionsl are right, and is 5 reilected out through the face I2c to the entrance or objective oi the telescope indicated in general as I4. Either' the telescope or the prism table is rotatable about an axis passing through or closelyiadjacent to the liquid glass interface in the viewed element, this axis generally being a perpendicular one. Means -for effecting carefully controllable and determinable movement of the movable element is provided, as the knobs I5 operating through appropriate gearing. These knobs are preferably calibrated to provide an in dication of the angle of movement, and conventionalmlcrome'ter means may be associated with the movable element'or with the knobs.

In accordance with conventional refractometer practice, the liquid to be observed is placed betweengthe appropriate facesoi the prisms and illuminated. .and then the movable element o! the reractometer is manually moved until transition from light to darlev is noted. The observer then endeavors to accurately center this transition. and it is in this latter phase that my refractmetr d'iii'ers from-the conventional one.

v now more particularly to Figui-es 3 to'G, it willbe seen-thatl the- -rear portion of my is Substantially Conventional. beine here shown'a'scomprisingtwosymmetrically disposed 'Ram'sden o culars with ahoriZoDtalslitB at the .exit pupillusinz beine electedthroueh the' l actionot the pinion'll o o-.theraelk ilwhenvthe. 35 vknob al! is. rotated, Inasm'uoh'as the-.rear -prge .'tionfr the-telescope provides thesame effects: axconver'xtional low power'telescope' it will not be. described. and attention',viriliA beturned.

in- Figure 4. e t u how. to this forward or novel vom' it wm be 'thatthe'lower 'of the tele-.'-

Immtely behhadtheen'anee slit-2l I'have provid o bipltteg-. .the

' plaies. and It. platea are ditpedata as. 'um f 'to en "van 16 the of the-reversing prism 2l. Bv

.to the. form@ wrt-1.09; that-M011 9111 f the-use o! these plates the ground glass upper surface oi the reversing prism, and the clamp' ing band 2l holding it in place, are eliminated from the field of view. That is. light :rays Elltering me plete u move downwardly, eltnoush they leave the plate parallel to'theirdir'ectlon o! entrance. Ind light rays entering the lower DIe il similarly move upwardly. portions 0! the reversing prism and of the plate are led which are somewhat spaced from the upper Suflace of the reversingprism. so that there is n0 distraction or undesired break in the held of view. The light rays leaving the biplete combination are delivered to the entrance pupil Il and viewed in conventional manner through the telescope.

' The image of the line of juncture o! the plates Il and 24 is preferably focused on the exit pupil slit or aperture Il, and if this is done e uniform field of view l; obtained provided the Juncture line bisects this apex-ture. Under certain circumstances it may be desirable to have this out of focus so that the view provided through the uppez-*haii o! the entrance pupil does not completely overlap the viewprovided by the lower hail. but only partially so. In any case. the width o! the entrance slit Il alnd the exltalit Il must be so chosen or ndJusted that the Yimnge passing through the exit alit liu entirely within the area o! the Pupil 0f the operator usingthe instruf ment, ainoe in the ultimate analysis it is in the eye o! the observer. in this particular instrument. that the Iuperpoation tak'es place. It will be underxtood. or oourse'. .tl1et the reversal.is from means providing a direct view of n. part of a field an'ected by a portion 0i laid interface. said part including the dividing line between the dark and light area.: of the interface; means simultaneously providing a view o! a similar part oi said field with the light and dark areas interchanged; means lor at least partially superimposin'g said views with the dividing lines parallel and the light areas o! each view at least partially registering with the dark area. of the other view: and means for changing the angle of view of said interface. this means including indicating means for providing an indication of the index of refraction. Y

3. In an instrument for investigating the light relracting ellect of a substance. said instrument having a viewing element operatively associated with an illuminated viewed element wherein light is reflected from the interface of two adjacent substances with dlii'erent refractive indices said viewing element including: a telescope having an eyepiece: means for permitting' part or the light entering the telescope to 'pus directly to the eye to provide a direct view oi a part of a field including the dividing line between the' dark and light areasoi the interface: means Vfor reversing part of the light entering the telescope before it is delivered'to' the eye-to provide a reversed view lneludingaaid dividing line but with 4the dark and lightareas-interchanged: and

means 4for at least partially lupex'lmposing .laid

viewswith the .light area of each view at least Substances without reversal thereof. a.: in the iight passim! through the'prism. whereby there is provided a direct view oi a part oi a tleld including the di vlding line between the dark and light areas of the interface and a reversed view including said dividing line but with the dark and iight areas lnterchanged; and means (or atleast partially superimposing said views with the light area o! each view at least partially superimposed on the dark area ci the other view.

6. The apparatus claimed in claim 5, including a bi-piate combination between'the prism and the compensating means on. theone hand and the eyepiece oi the telescope on the other hand, said inl-plate combination inciudlngmearis lor intercepting iight closely adjacent the dividing line between the direct and reversing light. paths. whereby only such iight is delivered t the eyepiece as was initially spaced trom said dividing line. the bl-plate combination being ao constructed and arranged as to converge the lisht passing therethrough sumeiently to close up the gap which would otherwise be left by the intercepting means.

7. in an instrument (or investigating the light neiracting etiect oi a substance. said instrument having a viewing element operatively associated with an illuminated viewed element wherein light is renected from the interfaced! two Vacilacent diiierentfl refractive indices. and

through which hai! of the light entering the telescope passes on its way to tbe eyepiece, the prism eiiecting n reversal bisecting the telescope and parallel to the nrst mentioned axis; a plate in the telescope adjacent the prism and through which the other haii o! the light entering the telescope t0 the eyepiece. this plate effecting the same reiiection loss in the light passing through it, but without reversal thereof, as in the light passing through the prism. this means providing s. direct view oi'ha part ot a ileld including the dividing line between the dark and light areas oi the interiaee. the prism providing a reversed view including said dividing line but with the dark and iight areas interchanged; means iur at least per- Lially superimposing said views with the light area oi.' each view at least partially superimposed on the dark area o! the other view; and a iai-plate combination between the prism and the plate on the one hand and the eyepiece o! the telescope one-o! laid elements is'movableabout axis.

said-viewing element includinma telescope bav- 4ing an eyepiece; a reversingy prisrnintbe telescope remt-fno, 2.515625.:

on the other hand. said bi-plate combination Including means for. intercepting light closely ad jacent the dividing line between the direct and reversing iight paths. the bl-plate combination being so constructed and arranged as to converge tbe light passing therethrough suiiiciently to close up the gap which would otherwise be left bythe' interceptiruz means, whereby onlysucb iight is delivered to' the eyepiece as was initially spacd'tron'i said dividinx line between the'direct SAMUEL column, line or rom', a. "o.' 191552- lieferte rms;

about an axial plane' passes on its wavl Substances without reversal thereof. a.: in the iight passim! through the'prism. whereby there is provided a direct view oi a part oi a tleld including the di vlding line between the dark and light areas of the interface and a reversed view including said dividing line but with the dark and iight areas lnterchanged; and means (or atleast partially superimposing said views with the light area o! each view at least partially superimposed on the dark area ci the other view.

6. The apparatus claimed in claim 5, including a bi-piate combination between'the prism and the compensating means on. theone hand and the eyepiece oi the telescope on the other hand, said inl-plate combination inciudlngmearis lor intercepting iight closely adjacent the dividing line between the direct and reversing light. paths. whereby only such iight is delivered t the eyepiece as was initially spaced trom said dividing line. the bl-plate combination being ao constructed and arranged as to converge the lisht passing therethrough sumeiently to close up the gap which would otherwise be left by the intercepting means.

7. in an instrument (or investigating the light neiracting etiect oi a substance. said instrument having a viewing element operatively associated with an illuminated viewed element wherein light is renected from the interfaced! two Vacilacent diiierentfl refractive indices. and

through which hai! of the light entering the telescope passes on its way to tbe eyepiece, the prism eiiecting n reversal bisecting the telescope and parallel to the nrst mentioned axis; a plate in the telescope adjacent the prism and through which the other haii o! the light entering the telescope t0 the eyepiece. this plate effecting the same reiiection loss in the light passing through it, but without reversal thereof, as in the light passing through the prism. this means providing s. direct view oi'ha part ot a ileld including the dividing line between the dark and light areas oi the interiaee. the prism providing a reversed view including said dividing line but with the dark and iight areas interchanged; means iur at least per- Lially superimposing said views with the light area oi.' each view at least partially superimposed on the dark area o! the other view; and a iai-plate combination between the prism and the plate on the one hand and the eyepiece o! the telescope one-o! laid elements is'movableabout axis.

said-viewing element includinma telescope bav- 4ing an eyepiece; a reversingy prisrnintbe telescope remt-fno, 2.515625.:

on the other hand. said bi-plate combination Including means for. intercepting light closely ad jacent the dividing line between the direct and reversing iight paths. the bl-plate combination being so constructed and arranged as to converge tbe light passing therethrough suiiiciently to close up the gap which would otherwise be left bythe' interceptiruz means, whereby onlysucb iight is delivered to' the eyepiece as was initially spacd'tron'i said dividinx line between the'direct SAMUEL column, line or rom', a. "o.' 191552- lieferte rms;

about an axial plane' passes on its wavl 

